Javascript test for IE Text Size (EG "Largest") or any other accessibility settings (high contrast etc)

Question

Hi,

We are looking for a way to collect usage stats of our users web browser/OS configuration in regards to accessibility to better understand the range of users we have. If I can find a way to collect this data via javascript then I can capture it in via our analytics tool (same as google analytics variables).

These are some of the things we would like to know

1. Users who have increased their text size (EG to "Largest in IE8). This would be different to the page zooming feature most modern browsers have.
2. High Contrast settings at the OS level.

Are there any javascript tests/tricks to check for these?.. I'm happy to try browser specific solutions.

Thanks!